The invention relates to services that are produced by means of an intelligent network and more particularly to services in which a situation that is failed for the service is successful for the actual network.
An intelligent network (IN) is able to provide a subscriber of a telecommunications network, such as a wired network or a mobile telephone network, with a plurality of various services. Such services include a virtual private network (VPN) which enables the use of private numbers, and a personal number in which the intelligent network reroutes the calls directed to a personal number in a manner controlled by the subscriber. An example of such an intelligent network is described in recommendations of the International Telecommunications Union (ITU-T) Q-1200 series. In the following, the invention and its background will be described by the terminology of recommendation ETS 300 374-1 CoreINAP, but the invention can also be used in intelligent networks implemented according to other intelligent network standards. Within the scope of the present application, the concept intelligent network also refers to other application platforms which provide similar types of services.
In the intelligent network, connection arrangements are separated from service control so as to provide intelligent network services which are independent of the connection arrangements. The equipment or network element carrying out the tasks determined by a service control function or service control functions (SCF) in the intelligent network is called a service control point (SCP). Within the scope of the present application, SCF and SCP are equal, and will hereinafter be called SCP. The SCP gives call set-up instructions to the exchange, or the exchange may inquire call set-up instructions from the SCP. Exchanges responsible for an intelligent network interface are called service switching points (SSP). They contain at least a service switching function (SSF) and a call control function (CCF). The call control function CCF is not a service associated with the intelligent network, but it is a standard function in exchanges, comprising high-level call handling functions of an exchange, such as setting up and releasing transfer connections. The service switching function SSF is an interface between the call control function CCF and the service control point SCP. Within the scope of this invention, the service switching point and the functional entity formed of the CCF and SSF are equal, and will hereinafter be called SSP.
In the conventional call set-up which takes place without the help of the intelligent network, telephone exchanges make independently all deductions associated with call routing. In the intelligent network, the SCP also makes deductions associated with the routing. A basic call state model (BCSM), defined in connection with the intelligent network, describes different phases of call control and includes the points at which the call control can be interrupted in order to start an intelligent network service. When the SSP detects that a call requires an intelligent network service, it interrupts call processing and contacts the service control point which invokes a logic program associated with the service. Upon invocation of the logic program, a service logic entity or service logic entities are created for the call, and their function determines the instructions which are transmitted by the SCP to the SSP at each call phase. Service logic defines the detection points in the call and connection process at which the service logic entities can have an interactive relationship with basic call and connection control features. Call set-up or call release can be temporarily interrupted at the SSP at these detection points and further call handling instructions can be requested from the service control point SCP. The SSP interprets the instructions obtained and starts the required call control functions. If the service switching point SSP succeeds in carrying out the functions according to the instruction it received, then call setup proceeds to the next phase, and no further instructions concerning the previous phase are requested from the SCP.
It is a problem in the above arrangement that situations which are failed for a service are successful for a switching point. In these situations the switching point continues call processing without requesting additional instructions, although the situation failed for the service. An example of such a service is a call list service, the purpose of which is to reach the subscriber. However, the call may be directed to a voice mailbox, in which case the situation is successful for the switching point but failed for the call list service.
An object of the invention is to solve the above problem and provide a method and equipment implementing the method so as to solve the above problem. The objects of the invention are achieved by a method which is characterized by defining for the service at least one special situation during which provisioning of the network service fails but the switching point operates successfully, defining an instruction for said at least one special situation, receiving at the detection point a message indicating the existence of the call related service for which the special situation has been defined, receiving at the switching point a first routing instruction either from a caller or the control point, checking said first routing instruction, detecting the special situation if the first routing instruction indicates the occurrence of the special situation, and following said instruction in response to the detection of the special situation.
The invention further relates to a method which is characterized by defining a special character by means of which the caller of the call that activated the service is able to indicate a special situation during-which provisioning of the call for the caller fails but the switching point operates successfully, receiving the special character at the switching point, detecting the special situation in response to the received special character, requesting a second routing instruction in response to the detection of the special situation, and transferring call control to the service control point.
The invention further relates to an intelligent network in which the methods of the invention can be applied. The intelligent network of the invention is characterized in that at least one special situation is defined for the service, it being failed for the service but successful for the switching point, an instruction has been defined for said at least one special situation, and the service switching point is arranged to detect the special situation and follow said instruction in response to the special situation.
The invention further relates to a service switching point of an intelligent network, suitable for use in the methods and intelligent network of the invention. The intelligent network service switching point of the invention is characterized in that the switching point includes memory means for storing at least one definition for a special situation and its instruction for at least one service, the special situation being failed for the service but successful for the switching point, checking means for checking if the received routing instruction leads to a special situation, and function means responsive to the checking means for carrying out the operation of the instruction.
The invention further relates to a service control point of an intelligent network, suitable for use in the methods and intelligent network of the invention. The intelligent network service control point of the invention is characterized in that for a control point service is defined at least one special situation during which provisioning of the service fails but connection set-up is successful, the control point includes reception means for receiving a situation message indicating the special situation, and management means are arranged to give new connection set-up instructions in response to the situation message.
The basic idea of the invention is to detect a service-related special situation and, as distinct from the prior art, to act in the special situation in a way that is suitable for the special situation and the service, such as inquire the caller in connection with a call list service if (s)he wishes her/his call to be connected to a voice mailbox. An advantage of this is that the service is able to influence the action that is taken in the special situation, whereby the objective of the service is achieved in the best possible way.
In a preferred embodiment of the invention, a special situation is detected not until a special character dialed by a caller is received. An advantage of this is that it also provides an opportunity to react to special situations on occasions in which the service switching point has not detected a special situation, because the voice mailbox is located in another exchange, for example, to which the switching point is connected via a telephone network, and the switching point is therefore unable to detect the special situation.
In a preferred embodiment of the invention, new instructions are requested in a special situation. An advantage of this is that the service gives further instructions by taking into account the instructions obtained from a subscriber of the service, for instance. The service may even request instructions from the caller, even though (s)he would not be the subscriber of the service. The caller is thus able to decide if (s)he wishes to leave a message in the voice mailbox or if (s)he wishes to still try to reach the called party, i.e. subscriber B, for example.
In a preferred embodiment of the invention, the service control point notifies the switching point that checking the special situation is no longer necessary. An advantage of this is that it is possible to change a service in the middle of a call to a service not having a special situation and to accept routing that leads to a special situation. For example, in the call list service routing to a voice mailbox is not accepted until all other numbers have been gone through.
In a preferred embodiment of the invention, an instruction for a special situation is defined at the service switching point. Thus, unnecessary signaling is avoided between the control point and the switching point. This is especially an advantage in special situations in which releasing the connection is more meaningful for the service than routing the call.
The preferred embodiments of the methods, intelligent network, service switching point and service control point of the invention are disclosed in the attached dependent claims.